Arduino SD - openNextFile()用法及代码示例

file.openNextFile()

#include <SD.h>

File root;
void setup() {
  Serial.begin(9600);
  pinMode(10, OUTPUT);
  SD.begin(10);
  root = SD.open("/");
  printDirectory(root, 0);
  delay(2000);

  Serial.println();
  Serial.println("Rewinding, and repeating below:");
  Serial.println();
  delay(2000);

  root.rewindDirectory();
  printDirectory(root, 0);
  root.close();
}

void loop() {
  // Nothing happens after setup finishes.
}

void printDirectory(File dir, int numTabs) {
  while (true) {
    File entry = dir.openNextFile();
    if (!entry) {
      if (numTabs == 0)
        Serial.println("** Done **");
      return;
    }

    for (uint8_t i = 0; i < numTabs; i++)
      Serial.print('\t');

    Serial.print(entry.name());

    if (entry.isDirectory()) {
      Serial.println("/");
      printDirectory(entry, numTabs + 1);
    } else {
      Serial.print("\t\t");
      Serial.println(entry.size(), DEC);
    }

    entry.close();
  }
}